Here's one that was sent in by one of my more valued colleagues. none other than Ferenc "Somi" Somogyi of Hungary. No dimensions were provided, but Somi stated that the engine has a displacement of 30 cc (1.831 cuin.). Classic engines of this displacement are generally intended for model boat applications, although this one looks far more like an aero unit to me. It's not a racing design per se - no front ball race. The present owner thought that it might be English, but gave no reasons for this view. Another colleague felt that it was a home-made job, although I have to say that it seemed to me to have a more "series production" air about it.
IDENTIFICATION MADE!! I heard from French reader Michel Rosanoff about this engine, which turns out to be a French product having an unusual and quite interesting history. Michel tells me that the design was originally sold in 1950 as the MICROMOTEUR 30 cc. It was made by Jacques Durand of Vitry sur Seine, a south-eastern suburb of the City of Paris. Like L.C. and R.E.A., the MICROMOTEUR was a product sold exclusively by the famous Paris model shop "La Source des Inventions”. It was apparently produced in anticipation of a rapid growth in the popularity of large R/C models, which did not happen at that time. As a result, the engine was withdrawn in 1951 with very few having been made. Sadly, the engine was just too far ahead of its time.
Later, in 1953, the same design was re-issued by the famous VEGA firm of Paris as the VEGA 3000. However, it met with no better success – only around ten examples were sold before the engine was once again withdrawn in 1954. Consequently, it’s a very rare engine indeed! Further details (in French!) may be found at this link.
This is a truly massive unit! Bore and stroke are 35 mm and 31 mm respectively for a displacement of 29.83 cc (1.82 cuin.). The monster weighed in at an impressive 750 gm (26.45 ounces). Claimed output was around 1 BHP @ 8,000 RPM.
My sincere thanks to Michel for sorting this one out!